The identification of substances which are potent proliferation inhibitors is of great importance during drug discovery, preferably in the field of oncology. There exists a variety of in vitro cell-based assays for the investigation of the antiproliferative effect of such candidate substances. Examples of such assays are, for instance, the MTT colorimetric assay, the [3H] thymidine uptake assay, and the WST assay (Johnston, P., in: Cellular Assays in HTS, Methods in Molecular Biology, Vol. 110, Janzen W. P. (ed.), Humana Press, NJ, pp. 107–116; Bellamy, W. T., Drugs 44 (1992) 690–708). In regard to drug development, it is preferable that such assays can be used in high throughput screening of large numbers of potential drug candidates.
For the determination of the proliferation status of hematopoietic cells, it is known to contact the cell population with the substance to be investigated (“test substance”) and a reagent capable of generating luminescence in the presence of ATP and detecting the luminescence as a measure of the proliferation status (US 2002/0146680). An assay for determining the number of cells in cell culture by fluorescence measurement is described in U.S. Pat. No. 5,972,639.
The above-described assays are time-consuming, provide only limited results, and do not discriminate between inhibition of proliferation and induction of cell death. Therefore, there exists a need for an assay that is simple to perform and allows the determination of the influence of a test substance on both cell proliferation and the induction of cell death simultaneously. Moreover, it would be preferable for such assay to be automated.